According to a report of the International Telecommunication Union (ITU), currently, nearly two-thirds of the world's population still has no access to the Internet, and is mainly distributed in remote areas with a low population density. Network coverage on these areas by using ground base stations has very high costs. An high-altitude platform (a balloon, an airship, or a drone) is a new means to provide a wide coverage network for the remote areas. Generally, a high-altitude platform is located in the stratosphere at an altitude of 18 km to 25 km above the ground. The stratosphere generally has a relatively low wind speed (for example, a wind speed of 5 m/s to 40 m/s) and relatively small turbulence. In addition, an altitude higher than 18 km generally exceeds a maximum altitude specified for a commercial plane. Therefore, when deployed at an altitude of 18 km to 25 km, a high-altitude platform does not cause much interference to a commercial plane.
In a related technology such as Project Loon, a high-altitude platform carries a base station (including a communications device such as a baseband unit (BBU), a remote radio unit (RRU), or an antenna) to rise to the stratosphere, and the high-altitude base station communicates with a ground core network through wireless backhaul. The high-altitude platform needs to take protection measures such as low temperature, low pressure, low humidity, and heat dissipation on the communications device, to prevent the device from being affected. The high-altitude platform is powered by solar cells.
During implementation of the present invention, the inventor finds that the prior art has at least the following problems:
Load of the high-altitude platform is directly proportional to a size and costs of the platform. Issues such as a volume, a weight, thermal insulation, heat dissipation, and power consumption of the base station moved to the high-altitude platform impose quite high requirements on a valid payload and a power supply capacity of the high-altitude platform.
Usually, a high-altitude device continuously moves in air, instead of staying at a specific location. When a wind speed is stable, the high-altitude device may roughly fly along a track with a radius R and a central location under the control of a flight control system. However, when the wind speed is unstable, for example, when there is atmospheric turbulence or the like, the wind speed and a wind direction change. Consequently, a moving rate of the high-altitude device relative to the ground changes, and the high-altitude device may fly out of a beam coverage area, thereby causing a free space link between the high-altitude device and a ground device to be unstable or even interrupted.